tyrion

So a wire connects the front light to the rear light. The shortest path would be along the top tube, down the seat to the rack struts, then the along the top of the rack. The alternative is along the down tube, along the chain stay, them up the rack. The top route is shorter, the bottom route is arguably a little more out of sight.

Which way should I go? (My top tube currently is "naked", all cables go down the down tube.)

(I just ordered the lights, haven't got them yet, but trying to think this through.)

Edit: the rear light will be attacked to the rear of the rack.

2_i 

Accidental and out of sight damage is more likely along the down tube, where well more is going on mechanically and where the route is closer to the ground. If you carry the bike on a car rack, then you presumably grab the bike by the top tube and the wires are then vulnerable there. Still, I would go along the top, choosing the wire color to match the frame. You can get zip ties for the tubes that lie flat.

Tourist in MSN

I have done both downtube and toptube.

How permanent/temporary is this? The more permanent it is, the more you want it to look nice and not snag on anything. The more temporary it is, the less importance you put on looks and the faster you can wire it. My temporary wiring jobs took no more than 10 minutes.

When I did toptube routing, that was temporary and just wrapped the wire around the brake cable between the cable stops, the light was mounted on the seatpost or on a seatstay.

I prefer the downtube routing. Permanent, I zip tie wires under the downtube. Temporary, I wrap the wire around a shift cable, assuming that a shift cable is on the side of the downtube.

I have not wired a rack taillight for permanent use, my permanent routing has been for fender mounted lights. My rack wiring was always temporary.

Rack mounting, I used zip ties to run the wire down to the non-drive side dropout from the light and then wrapped the wire around the chainstay so that it is fairly ugly. The role of the zip ties on the rack routing was to make sure that rack top bags or pannier brackets did not damage or snag any wiring. I put more care in the wiring on the rack than anywhere else.

I have not run the wire along a drive side chain stay, but that certainly would be do-able, you could wrap the wire around the shifter cable forward from the cable stop on the chainstay and all the way up to near the headtube.

A few weeks ago I changed one of my ugly temporary wiring jobs to a permanent wiring job. One thing I did on that was that the wire where it transitions from the frame to the fork, I wrapped the wire around something so that it was in a coiled shape. Dipped that in nearly boiling water for about 10 seconds, let it cool, and that wire now is coiled for when I turn the bars to the side it can expand or contract in length. I have no clue if that coiling will last or not, but so far it looks nice. I have no photos yet.

If you are curious, I sometimes do not have rear racks on bikes, I use different racks for riding around town than I use for touring. Thus, I do not want to use a permanent mounting and wiring on a rack because on my bikes, racks come and go.

kingston 

There's no way I would ever run a tail-light wire on a bare top tube on one of my bikes. I run the tail-light wires with the cables and use shrink-wrap on outers and little o-rings on exposed inner cable to keep the electrical wire in place. I would use whatever cable got me closest to the rack then probably electrical tape or zip-ties to route it up the rack to the light. For fender lights I drill a little hole, put a rubber electrical grommet in there and use foil hvac tape to stick it to the underside of the fender.

tyrion

Very permanent. I want to force a thief to think and work a lot in order to steal my lights. Might even super glue nuts on bolts.

downtube42

Top tube for me. I use clear 3M tape for a very clean look.

Tourist in MSN

So, you live in a place where thieves know what the cost of a light is? Perhaps I am fortunate, thieves here are mostly opportunistic. But a small number are somewhat knowledgeable and look hard for expensive looking carbon bikes. I do not worry much about locking up my S&S Rohloff bike, thieves would not know what it is worth. But my titanium bike with a Deore rear hub looks valuable to them so I use a $100 lock on it.

If you really are concerned about the nuts, those allen wrench type nuts on rim brake pads are a standard M6 thread. A thief would need to have an allen wrench to get one of those off, or a big vice grip.

And there are different categories of loctite threadlocker compounds. I have only used blue (removable) but there is one or more that need heat to remove the nut. Thus, if you had to remove it, you could. I would not use super glue.

On most of my bikes with dynohubs, I use a bolt on skewer instead of quick release. And when touring I use bolt on skewers front and rear. I am assuming thieves are opportunists and I am trying to slow them down. They are not a special locking type skewer with a special key, they use a regular 5mm allen wrench. And I keep a spare allen wrench with my spare tube for obvious reasons. I do not ones that take a special key that I might lose.

Germany_chris

I run mine down the downtube then into the fender

alo

The wiring will probably look messy. I would get a solar tail light, and eliminate the need to run a wire to the back of the bike.

Chuck M 

Any specific reason for wanting/needing a dynamo light? So many modern lights mount with quick releases and are usb rechargeable that it would eliminate your wiring and theft concerns.

Trevtassie

I got some thin black truck airline. Looks like cable outer, ran that along the top tube using the cable mounts already there, then down onto the rack, wire goes inside.

tyrion

So I don't have to worry about charging batteries.

unterhausen

I'm trying to remember a time when the wiring on one of my bikes wasn't "temporary."
I use gorilla repair tape to hold it to bare tubes, and usually it doesn't look too bad for a couple of years. The part that makes it look bad is that I don't trim the wires because it's just temporary.

I use dyno taillights on all my bikes because I have had battery lights go out on me and I don't want that to be the only light I'm using. I actually had 2 battery lights die on the way home from work one very cold day. It was 5F, which is not a good temperature for batteries.

Tourist in MSN

This is one of two bikes that I considered my wiring to be permanent. Note, no rear rack, sometimes I have a rack on that bike and sometimes not. I built up the bike in spring 2017 and finished the wiring in spring 2018.

Took the photo about three weeks ago, lake behind it was still frozen. I typically have a flashing battery taillight on bikes, here I mounted a battery light on the seatstay mount for the rack.



Photo below is a year and a half old, I had a rack on the bike at that time. Spaninga Pixio (spell?) taillight with guard on fender, wiring is glued inside the fender.



Older photo, bottom bracket area. The wire that I glued under the fender was a poor choice on my part, it is a fairly heavy two conductor wire, one side is red. I say it was a poor choice because it was stiff enough that it was hard to glue it in place. I drilled a hole in the fender and the wire exits the fender at that hole, which you can see because one side of the wire is red. I wanted disconnects in the wire here in case I needed to disconnect something later, used 2.8mm spade connectors as my disconnect there. From there the wire goes under the bottom bracket and up underneath the downtube. That wire under the downtube is two wires, twisted together, I think it is about 18 or 20 gauge. You can see the twisted pair of wires under the downtube.




Year and a half old photo, Luxos U headlamp. I custom bent the bracket for the lamp, but there are similar B&M brackets available. I needed a longer bolt for the fork crown than was readily available at the hardware store, used threaded rod instead. You can see the wire under the downtube is two separate wires, twisted together, zip tied to downtube.

If you are confused by the brake, yes there is a disc brake on the back wheel, rim brake on the front, travel agent on the front brake to convert cable pull to normal road brake lever pull ratio.




I used the same twisted wire to the hub from the light, zip tied to the fork.



I mentioned earlier in this thread that I usually use bolt on skewers on dynohub wheels, you can see that in the above photo.

I mentioned earlier in this thread that one of my other bikes stopped having temporary wiring, now has permanent wiring, when I get photos of that I will post them. I did a much better job of gluing the wire under the fender on my second "permanent" wiring job. And I took photos of the gluing process.

Moe Zhoost

I've always routed the wire along the top tube; however that was specifically to follow the brake cable routing. I use 3mm coax cable and anchor it to the cable housing with small o-rings. Consider routing your wires inside your tubes. I've thought about this a bit. The coax is really thin so you would just need to drill a small hole in the downtube right behind the head tube. From there, I'd probably run it down the downtube into the BB shell and then up the seat tube into the seat post and out through a small hole in the top.

Good luck on your project.

kingston 

Everyone's different. Apologies if my earlier post came off as rude. I didn't intend it that way. I'm a matching wheelset hidden wire kind of person, so my 4 bikes with dynamo lighting are all permanent installations.

I have thought about rigging something up with a velogical dynamo that I could use on more than one bike, but honestly I'm totally fine with battery lighting most of the time. On brevets I'm usually not in the dark all that long and can bring a bike with a dynamo if I think I will be.

PaulRivers

My concern with mounting location is avoiding putting the wire anywhere it might suffer wear.

Downtube, bottom: this is where my front tire kicks all the road grit onto. Worst spot, in my opinion.

Downtube, top: probably the best spot, I can't think of anything that would cause wear here. Also likely the most aesthetic.

Top tube, bottom: the only thing that might cause wear here is if you carry the bike on a hold-by-the-frame rear rack. Aesthetically it would stick out a bit more. 2nd best spot.

Top tube, top: I wouldn't want to deal with the possibility of catching the wire with my foot when swinging a leg onto the bike - something you do at least once each ride.

So in my opinion best spot is the the downtube, on the top of it. Basically run the wire right next to the water bottle cage.

tyrion

I think I will copy that idea. Thanks.

noglider 

The air hose does sound like a clever idea, but do wires get ripped in the middle? The only troubles I can remember having have been wires pulled out of the connector at the dynamo or light.

sweeks

B&M also makes a rear light that monitors the frequency of the AC coming from the dynohub. When the frequency drops suddenly, as it would when braking, the rear light brightens. Brake light function with no actual connection to the brakes!
My tail light wire runs down the down tube and along the NDS chainstay then up the rack.
I have the headlight (B&M IQ-X) mounted on one of the V-brake studs because my fork does not have a hole through the crown...

sweeks

I've used brake cable housing with a wire inside for the computer sensor connection on my folding commuter bike. The metal spiral serves as one connector and the wire is the other. It's almost bullet-proof... not a bad thing where the bike parts are constantly being folded and realigned.

tyrion

I ordered B&M's magical brake light (Top Line Plus) along with the IQ-X.

Tourist in MSN

The Topline rack mounted light, I had one on a rack and when I went to remove it I found that the nuts were rusted on to the bolts and that the bolts twisted in their plastic mount inside the light.

I suggest you put a nut on each bolt first, then mount it to the rack, and then use a second nut that is stainless on each bolt. Then if several years from now you go to remove it from the rack, you can two wrenches, put a wrench on each nut to unthread it. And maybe some washers too.

unterhausen

I have always been afraid to use the topline light that I bought that has the brake light. I'm almost positive I ordered the non-brake light version.

2_i 

Same here with IQ-X. I stay away from overly fancy, overly specialized lamps/devices that can easy stumble.

Isn't using just stainless steel nuts simpler? I normally replace anything that can rust and is replaceable anyway as the first order of business.